(Beyond Pesticides, December 2, 2011) The U.S. Environmental Protection Agency (EPA) has opened a pesticide docket for information and reviews relevant to insect resistance management for plant-incorporated protectants (PIPs) -plants engineered through biotechnology to express pesticidal properties. The agency intends to collect public information on insect resistance management and monitoring for genetically engineered (GE) PIPs after expressing concern that efforts to tackle resistance issues need to be “more proactive” and effective in light of “severe” and rapidly growing insect resistance to GE crops.

According to EPA’s Biopesticides and Pollution Prevention Division, the agency is reviewing insect resistance management assessments submitted by registrants in accordance with the ongoing terms and conditions of their registered PIP products. PIPs are genetically engineered to incorporate pesticidal properties in plant genes in order to ward off insects that prey on the plants. PIPs are registered as a pesticidal product under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). Many GE plants such as corn, cotton and others include Bacillus thuringiensis (Bt), a bacterium with insecticidal properties whose genes have been incorporated into the plant’s own genetic material. However, recent reports have shown that these PIPs are spawning “superbugs” that have become resistant to this technology. Monsanto, the lead manufacturer of PIPs, has created several Bt genes including one called Cry3Bb1 which has been responsible for resistant populations of western corn rootworm no longer susceptible to Bt.

According to documents in the newly opened docket, (Docket No: EPA-HQ-OPP-2011-0922) EPA reviewed Monsanto’s resistance monitoring data from 2009 for the western rootworm which was submitted for registrations on Bt corn containing the Cry3Bb1 gene. The agency concludes that based on multiple documented cases of unexpected “severe” corn rootworm damage to Cry3Bb1 fields and other undocumented reports from corn entomologists, “Cry3Bb1 resistance is suspected in at least some portions of four states in which “unexpected damage” reports originated and recommends that the Cry3Bb1 remedial action plan be implemented for “suspected resistance.” Further, EPA states that the registrant’s (Monsanto) current resistance monitoring program is inadequate and likely to miss early resistance events, stating for efforts to be meaningful “a more proactive, effective approach needs to be adopted.”

Roughly one-third of the corn grown in the U.S. carries Monsanto’s Cry3Bb1 gene, which means that, should populations of this rootworm spread, corn farmers across the U.S. will be faced with heavy losses. Researchers from Iowa State University discovered western corn rootworms in four Iowa fields that have evolved and can resist the pesticide built into Bt corn seeds. So far the cases are isolated, but can spread to neighboring regions. Farmers in Illinois, for example, have been seeing severe rootworm damage in fields planted in Monsanto’s Bt corn.

This past year EPA has been in touch with scientists in academia and at USDA-ARS regarding Bt cron resistance issues in the Mid-west, notably Iowa, Illinois, Nebraska, and Minnesota. In Nebraska, the 2011 growing season marked the fourth year where moderate to severe rootworm damage in Monsanto’s Cry3Bb1 corn was apparent. Resistance monitoring data for Cry3Bb1 show that field-collected populations are generally less susceptible to the toxin.

In 2009, every field-collected populations of rootworm had higher LC50 (concentration needed to kill 50 percent of the population) than laboratory controls, in some cases by an order of magnitude. Monitoring data collected from 2005 to 2009 appeared to show a large decrease in susceptibility over the time period. One county in Illinois showed a six-fold increase in mean LC50 from 2007 to 2008 (50.2Î¼g/cm2 in 2007 to 300.9Î¼g/cm2 in 2008). Contributing to the growing resistance is the domination of monoculture crops in this region. Records show that affected fields have been growing Monsanto’s Cry3Bb1 corn for many successive years without crop rotation. In fact, according to the data collected, a significant positive correlation was detected between the number of years growers chose to plant Cry3Bb1 and the survival on Cry3Bb1corn of insects from problem fields. Unfortunately, many growers still plant the Bt corn despite the incidences of rootworm damage and fall back on pesticide applications to control the adult corn rootworm.

Resistance to GE crops is not new. “Roundup Ready” crops engineered to survive exposure to Monsanto’s Roundup herbicide, a glyphosate-based chemical, has also spawned a new generation of Round-up resistance weeds dubbed “superweeds.” These weeds, immune to Roundup, have spread to millions of acres in more than 20 states in the South and Midwest. In addition to resistant weeds, heavy use of Roundup sprayed on “Roundup Ready” crops appear to be causing harmful changes in soil and potentially hindering yields of crops that farmers are cultivating according to scientists at the USDA’s Agricultural Research Service. Growing previous Roundup Ready crops, such as soy, cotton, and corn, have also led to greater use of herbicides, especially when these crops fail to control the pests they are marketed to thwart.

All unattributed positions and opinions in this piece are those of Beyond Pesticides.

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